Opc.Ua.Server.Session.ValidateRequest C# (CSharp) Method

        public virtual void ValidateRequest(RequestHeader requestHeader, RequestType requestType)
        {
            if (requestHeader == null) throw new ArgumentNullException("requestHeader");
            
            lock (m_lock)
            {
                // get the request context for the current thread.
                SecureChannelContext context = SecureChannelContext.Current;

                if (context == null || !IsSecureChannelValid(context.SecureChannelId))
                {
                    UpdateDiagnosticCounters(requestType, true, true);
                    throw new ServiceResultException(StatusCodes.BadSecureChannelIdInvalid);
                }
            
                // verify that session has been activated.
                if (!m_activated)
                {
                    if (requestType != RequestType.CloseSession)
                    {
                        UpdateDiagnosticCounters(requestType, true, true);
                        throw new ServiceResultException(StatusCodes.BadSessionNotActivated);
                    }
                }

                // verify timestamp.
                if (requestHeader.Timestamp.AddMilliseconds(m_maxRequestAge) < DateTime.UtcNow)
                {
                    UpdateDiagnosticCounters(requestType, true, false);
                    throw new ServiceResultException(StatusCodes.BadInvalidTimestamp);
                }

                // request accepted.
                UpdateDiagnosticCounters(requestType, false, false);
            }
        }

        /// <summary>
        /// Validates request header and returns a request context.
        /// </summary>
        /// <remarks>
        /// This method verifies that the session id valid and that it uses secure channel id
        /// associated with with current thread. It also verifies that the timestamp is not too
        /// and that the sequence number is not out of order (update requests only).
        /// </remarks>
        public virtual OperationContext ValidateRequest(RequestHeader requestHeader, RequestType requestType)
        {
            if (requestHeader == null)
            {
                throw new ArgumentNullException(nameof(requestHeader));
            }

            Session session = null;

            try
            {
                lock (m_lock)
                {
                    // check for create session request.
                    if (requestType == RequestType.CreateSession || requestType == RequestType.ActivateSession)
                    {
                        return(new OperationContext(requestHeader, requestType));
                    }

                    // find session.
                    if (!m_sessions.TryGetValue(requestHeader.AuthenticationToken, out session))
                    {
                        var Handler = m_ValidateSessionLessRequest;

                        if (Handler != null)
                        {
                            var args = new ValidateSessionLessRequestEventArgs(requestHeader.AuthenticationToken, requestType);
                            Handler(this, args);

                            if (ServiceResult.IsBad(args.Error))
                            {
                                throw new ServiceResultException(args.Error);
                            }

                            return(new OperationContext(requestHeader, requestType, args.Identity));
                        }

                        throw new ServiceResultException(StatusCodes.BadSessionIdInvalid);
                    }

                    // validate request header.
                    session.ValidateRequest(requestHeader, requestType);

                    // return context.
                    return(new OperationContext(requestHeader, requestType, session));
                }
            }
            catch (Exception e)
            {
                ServiceResultException sre = e as ServiceResultException;

                if (sre != null && sre.StatusCode == StatusCodes.BadSessionNotActivated)
                {
                    if (session != null)
                    {
                        CloseSession(session.Id);
                    }
                }

                throw new ServiceResultException(e, StatusCodes.BadUnexpectedError);
            }
        }